add go.mod as supporting files to go-server (#4592)

Author: lwlee2608

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/GoServerCodegen.java

@@ -165,6 +165,7 @@ public void processOpts() {
         supportingFiles.add(new SupportingFile("openapi.mustache", "api", "openapi.yaml"));
         supportingFiles.add(new SupportingFile("main.mustache", "", "main.go"));
         supportingFiles.add(new SupportingFile("Dockerfile.mustache", "", "Dockerfile"));
+        supportingFiles.add(new SupportingFile("go.mod.mustache", "", "go.mod"));
         supportingFiles.add(new SupportingFile("routers.mustache", sourceFolder, "routers.go"));
         supportingFiles.add(new SupportingFile("logger.mustache", sourceFolder, "logger.go"));
         supportingFiles.add(new SupportingFile("api.mustache", sourceFolder, "api.go"));

modules/openapi-generator/src/main/resources/go-server/go.mod.mustache

@@ -0,0 +1,5 @@
+module {{gitHost}}/{{gitUserId}}/{{gitRepoId}}
+
+go 1.13
+
+require github.com/gorilla/mux v1.7.3

modules/openapi-generator/src/main/resources/go-server/main.mustache

@@ -5,14 +5,7 @@ import (
 	"log"
 	"net/http"
 
-	// WARNING!
-	// Change this to a fully-qualified import path
-	// once you place this file into your project.
-	// For example,
-	//
-	//    sw "github.com/myname/myrepo/{{sourceFolder}}"
-	//
-	{{packageName}} "./{{sourceFolder}}"
+	{{packageName}} "{{gitHost}}/{{gitUserId}}/{{gitRepoId}}/{{sourceFolder}}"
 )
 
 func main() {

samples/server/petstore/go-api-server/go.mod

@@ -0,0 +1,5 @@
+module github.com/GIT_USER_ID/GIT_REPO_ID
+
+go 1.13
+
+require github.com/gorilla/mux v1.7.3

samples/server/petstore/go-api-server/main.go

@@ -13,14 +13,7 @@ import (
 	"log"
 	"net/http"
 
-	// WARNING!
-	// Change this to a fully-qualified import path
-	// once you place this file into your project.
-	// For example,
-	//
-	//    sw "github.com/myname/myrepo/go"
-	//
-	petstoreserver "./go"
+	petstoreserver "github.com/GIT_USER_ID/GIT_REPO_ID/go"
 )
 
 func main() {